CODEWITHSUNDEEP
iosswift3nspredicate
KMC
KMC

Reputation: 1742

NSPredicate throwing EXC_BAD_ACCESS

I'm trying to delete books that user selected and I'm getting EXC_BAD_ACCESS at NSPredicate line. Can anyone tell me where am I doing wrong?

 func deleteSelectedBook() {
    // Create Fetch Request
    let fetchRequest = NSFetchRequest(entityName: "BookEntity")

    // Create array string for predicate
    var titleCollection:[String] = []
    var formatString:String = ""
    if let selectedCellCollection = self.tableView.indexPathsForSelectedRows {
        for index in selectedCellCollection{
            if (!formatString.isEmpty) {
                formatString += " OR "
            }
            var temp = (self.tableView.cellForRowAtIndexPath(index)?.textLabel?.text)!
            titleCollection.append(temp)
            formatString += " title = %@ "
        }
    }

    // Configure Fetch Request
    fetchRequest.predicate = NSPredicate(format: formatString, titleCollection)

 ......

Upvotes: 0

Views: 464

Answers (1)

Martin R
Martin R

Reputation: 540055

For two (as an example) selected items the formatString would be

"title = %@ OR title = %@"

which expects two arguments, but in

NSPredicate(format: formatString, titleCollection)

only one argument is given. You could fix that with

NSPredicate(format: formatString, argumentArray: titleCollection)

where the titleCollection now provides all arguments for the predicate creation. But a better and simpler solution is

NSPredicate(format: "title IN %@", titleCollection)

with a fixed predicate format string.

Generally one should avoid to use string manipulation to create predicate format strings. In this case a simple predicate serves the same purpose. In more complicated cases, NSCompoundPredicate can be used to build a predicate dynamically.

Upvotes: 1

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